I. Field of the Invention
The present invention relates to a method for measuring antioxidant activities of samples and method for diagnosing diabetes or hyperlipidemia using the same.
II. Description of the Related Art
Methods for measuring antioxidant activities of samples, that is, the activities to prevent oxidation of other substances, are known. For example, WO92/10759 discloses a method for measuring antioxidant activity of blood plasma for the purpose of diagnosing myocardial infarction or for diagnosing conditions of a patient for the likelihood of onset of myocardial infarction. In this method, blood plasma which is a test sample, metmyoglobin, hydrogen peroxide, a coloring agent such as 2,2'-azinobis(3-ethylbenzthiazoline 6-sulfonate) (hereinafter referred to as "ABTS") are reacted and the absorbance after the reaction is measured. With this method, if the antioxidant activity of blood plasma is high, oxidation of metmyoglobin by hydrogen peroxide is inhibited by the blood plasma, so that coloring is inhibited. On the other hand, if the antioxidant activity of the blood plasma is low, oxidation of metmyoglobin by hydrogen peroxide is not inhibited very much, so that coloring is not inhibited very much accordingly. Therefore, by measuring the absorbance of the reaction mixture after the reaction, the antioxidant activity of the blood plasma can be measured.
Needless to say, it is advantageous to provide a method for measuring antioxidant activities of test samples, whose sensitivity is higher than that of the above-mentioned conventional method.